I passed JLPT2 a while ago and got an Android yesterday. Been looking for a Japanese learning app that does not focus on simple phrases + hiragana/katakana. I'm also not that keen on having an app that just uses one of the freely available kanji lists and just makes you drill those. Would like some more vocabulary-oriented app.
Are you familiar with the program Anki? It has many shared decks to study from, many of which relate to Japanese. The app Ankidroid is the android version and highly recommended. Some advice on Japanese decks can be found if you browse the 'kanji koohi' site. For intermediate studies - if you concentrate on reading - Japanese Vertical text viewer is good - and it will give you proper Japanese font support - as the Android system fonts sometimes seems to use Chinese characters that don't look right for Japanese. Any new vocabulary you pick up, you can review later with Ankidroid, if you want to. Also, I really like rikai - it's in its early stages but seems to work well. Use it to browse Japanese web pages, with access to a handy pop-up dictionary definiton for any Japanese word.